<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  
  <style>
    /* css的注释 */
    .box {
      font-size: 30px; /* 字体大小 */
      color: red; /* 前景色 */
    }
  </style>
</head>
<body>

  <div class="box">我是盒子</div>
  
</body>
</html>